Lapping machine



F. A. KERSHAW. LAP'PING MACHINE. A'PPLICATION FILED APR.1.0, 1919.

f m M m im m I W @m J F. A. KERSHAW. LAPPING MACHINE,

APPLICATION FILED APR. 10, 1919.

Patented Nov. 7, 1922';

2 SHEETS mjZUQTZtOIP flaw 33% Patented Nov. 7, 1922.

UNETED STATES FRANCIS A. KERSHAW, or KENT, onto.

1 Q1 LAPPING MACHINE.

Application filed April 10, 1919. Serial No. 289,107.

To all whom it may concern:

Be it known that I, FRANCIS A. KnRsHAw, a citizen of the United States, residing at Kent, in the county of Portage and State of Ohio, have invented a certain new and useful Improvementin LappingMachines, of which the following is a full, clear, and exact description.

This invention relates to that type of apparatus known as a lapping machine, and has forits chief object to provide a machine so constructed and operated as to produce accurate parallel plane surfaces on the articles being lapped, especially gauges which are to have great accuracy, and are generally known to machinists as precision gauges.

A further object is to so mount and operate the laps and the holder for the work or gauge blanks that the blanks will be acted on by 'all portions of the lapping surfaces so as to maintainthe latter in parallelism.

In the machine constituting the subject matter of this invention, the lapping surfaces are the opposing parallel faces of two lap rings which are rotated by a spindle, and the blanks to be lapped are "in a holder which may be in the form of a ring or flat plate between the lapping surfaces, which holder is operated on by eccentrics or equivalent devices which give the holder a movement such that all the blanks of the holder will have a similar motion with respect to the rotating lapping surface, such that they travel back and forth, with an orbital movement from one edge or periphery of the lapping surfaces to theother.

The invention may be brieflysummarized as consisting in certain novel combinations and arrangements of parts and details of construction which will be described in the specification and set forth in the appended claims.

In the accompanying sheets of drawings, Fig. lis a side elevation of my improved lapping machine, parts being broken away for the sake of clearness; Fig. 2 is a top plan. view of the same; Figs. 3 and 4 are respectively a detailyertical and horizontal sectional view through the hubs of the lap holders.

The machine includes a base 10, which may. if desired. be in the form of an oil pan, but which will have suflicient rigidity to adequately support in proper relationship the working parts of the machine. The base whichin itself may be mounted upon legs 11, has suitable journal bearings lfZ for a vertical spindle 13, which may be driven by a belt pulley 14, or otherwise. v Secured to the spindle abovethe base 10 is a lower lap holder 15, with a downwardly extending hub 1'5 which may havela tight fit on the shaft, and is secured thereto by a key, set screw, or otherwise, and having an upper hub l5 whose bore is somewhat larger than the diameter ofthe shaft. Q

Above the lap holder 15 is a second lap holder 16 with an upper hub 16 and a lower hub 1 6 which may have a close working fit on the spindle, and the lower hub has a close sliding fit in the hub 15 of the lower lap holder 15. The two interfitting' hubs are connected together by oppositely disposed feathers which allow the two lap holders to move axially on the shaft, one relative to the other, while at the same time constraining them to rotate inunison. Secured to the upper side of the lower lap holder 15 and to the lower side of the upper lap holder are two laps or lap rings 17 and 18, whose opposing parallel faces constitute the lapping surfaces. 'The construction is such that both lap rings .17 and 18 will be rotated together with the opposing lapping surfaces traveling in true parallel planes, insuring that'the gauge blanks or other articles placed between the laps and operated on simultaneously by the opposing lapping surfaces will have produced on their opposite surfaces parallel planes of great accuracy.

Gravity may be relied onto produce the lapping pressure, but if gravity is not sufficient, I may employ a" spring such as shown at 19. and located between the upper lap-holder16 and an adjustable nut or handwheel 20 on the upper end of the spindle. From this it will be seen that the pressure exerted on the blanks being lapped can be varied as much as desired adjusting the hand-Wheel 20. f

Supported from the base 10 by columns 21 or otherwise, is a horizontal ring 22 which surrounds the lower lap ring 17, and mounted to slide horizontally over the top surface of this ring is a flat circular plate 23 to which is secured the work or blank holding plate 245. in this case in the formof a ring or annulus. this blank holder extending in wardly between the lapping surfaces, as clearly shown in Fig. 1. This blank holder will have a number of openings spaced around the same for blanks such as shown at 25, which as before, may be, and usually are gauge blanks. The shape of the openings will, of course, depend upon the shape or outline of the blanks, which may be circular, square, or other shape.

, The work holder 24 is not stationary during the lapping operation, but is given a motion such that each blank, no matter where it is located in the blank holder, will have an orbit, in this case, a circular orbit, which causes the blank to move inwardly and out- Wa dly' b twe n the, per pher e of the ati lappi g urf ces 1 his nst nce the 12lat23 hi arri s thelb enk hold 2 's. ac uated by wo imilar met i 26 h ch e dispesed on diam tr l y QPPQ e sid o he. ma hine a d. are rece ed in circular openings in: extensions 23?. of the hel rs 2.3- Thes e e tr c a e nte with sleeves 27 mounted on vertical studs 27%. asd' h s rotated bye gear ntegral with or fixed to the sleeve 27,. and by idler gear 29, and a relatively large gear 30, the latter being secured so as to be re tated by the spindle 13. The spindle 27 and idler gears 29 are suitably supported from th s '10- I Thus it will be seen that; through the motion imparted b the e centrics'QG, every p in ft ele. holde 2%: esc' ihssa i a z rawls in; a us ie s was. di m: tar eq al to t th ibw at the Bnt s wh th ow senses tqm th lb a entirely ite s. as upp ng surfaces. Pref,-

eraibly theinner." portions of the blanks will whenin their extreme innermost position extend slightly beyondthefinner edges of the lappingsurfaces, and the outer portions of the blanks will when intheir outermost positions extend slightly beyond the outer edges of the lapping surfaces. Preferably the numberof teeth of the gears 28 and 30 are so selected that a large number of. revolutionsof the, lap ringswill be required before blank in the blank holder will occupy h sam eesiti n re ative. o. t a pin sir-isms t atit'ocupie ny P ns, sea Isytevent, h re t e. angul r p ds th g a 13 and 3. wil bev s h ha -isl panora a n er o m ee be kjill sea o wnp ree. l pping surf es; h s as r s t e a enance of the original truly parallel relations ship of the opposing. lappinglsurfaces, and absolutely prevents the formation of grooves, shoulders, or irregularities in the lapping surfaces. Y

The blank holder need not beinfthe' form of a continuous ring as shown, but in some instances the. blank; holding meansmay cons sist of a series of arms secured to and extendingi-nwardly from the supporting and. dri-ving'memben, in which event, the. inner ends-s Le is; bet e n. as ap;

mg means for receiving blanks, meansfor ro atin e aps, and ns e ua in hsblank hqlder-fl ith ea h iiq n thereo is moved between and in a plane parallel to the lapping; surfaces about a fixed axis different. from the axis of movement. of every point thereof and so that at least a part of each blank receiving means is at all times between thelapping surfaces.

2. In a lapping machine, a pair of opposing laps rotatably mounted and provided with fiatparallel lapping'surfaces, a blank holder extending between the laps, means for rotating the laps, and means for actuat ingthe blank holder so that each point of th lank 9191. 1 s a x d Orb t-a1 p th between and in a plane parallel to the lap ping; surfacesdifierent than the fixed orbital Path f a' beer re ns n s ifi' eetia di e r to cau the lan s be. carried k d forth s s t e. l pping area w th hollyp ss om. tweei th lapping surfaces at any point.

' 3. In a lapping. machine, a pair of laps rotatably mounted and provided withopposing lapping surfaces, means comprising a shaft disposed centrally with respect to the laps for rotating the. same, a work holder extending between the laps, and means operatively connected to the work holder independently of the bearing of the shaft for actuating the work holder so that each point thereof iswgiven an orbital movement between the, rotating lapping surfaces and in a. planeparallel to, the latter.

Ina lappingmachine, pair of opposing laps 'rotatably' mounted, means for :0,- tating said laps, a work holder extending be w n the l p an means oper y e nectedto the wcrkholder laterally outside of ,the. lappin surfaces for actuating. the holder so. that each point therof has an .01:- bital movement sufficient to carry the work back and forth across the rotating lapping surfaces and in a plane parallel to the latter.

5. In a lapping machine, a-pair of opposing laps rotatably mounted, means for rotating said laps,.a work holder extending between the laps, and means comprisinga. plurality of eccentrics engaging thework holder for actuating. the same so that each p ia tha eflss n Q i el. eas ent S rea ises I a 3 cient to carry the Work back and forth across faces or actuating the holder so that each 10 the rotating lapping Surfaces and in a plane point thereof has an orbital movement sufiiparallel to the latter. cient to carry the Work back and forth across 6. In a lapping machine, a pair of opposthe rotating lapping surfaces and in a plane 5 ing laps rotatably mounted, means for roparallel to the latter.

tating said laps, a Work holder extending In testimony whereof, I hereunto my 15 between the laps, and means comprising a signature.

plurality 01": eccentrics engaging the Work holder laterally outside of the lapping sur-' FRANCIS A. KERSHAW. 

